Growth and optical properties of ZnO nanorods by introducing ZnO sols prior to hydrothermal process

ZnO nanorods of 25 nm with quite homogeneous size and shape have been fabricated by introducing ZnO sols as nucleation centers prior to the hydrothermal reaction. The samples were characterized by scanning electron microscope, transmission electron microscope, X-ray diffraction, photoluminescence and resonant Raman spectra. After ZnO sols are introduced, the width of the resulting nanorods decreases above an order of magnitude and the aspect ratio increases 5 times. The increase of the intensity ratio of ultraviolet to visible emissions in room-temperature photoluminescence spectrum and the decrease of the Raman linewidths show the improvement in the quality of ZnO nanorods. Influences of the number of seed nuclei and the aging time of ZnO sols on the morphology of ZnO nanorods are discussed.     

Carbon nanostructures and graphite-coated metal nanostructures obtained by pyrolysis of ruthenocene and ruthenocene-ferrocene mixtures

Pyrolysis of ruthenocene carried out in an atmosphere of argon or hydrogen is found to give rise to spherical nanoparticles of carbon with diameters in the 10–200 nm range. Pyrolysis of ruthenocene as well as mixtures of ruthenocene and ethylene in hydrogen gives rise to spherical nanoparticles, which contain a high proportion of sp ³ carbon. Under certain conditions, pyrolysis of ruthenocene gives rise to graphite coated ruthenium nanoparticles as well as worm-like carbon structures. Pyrolysis of mixtures of ruthenocene and ferrocene gives rise to nanoparticles or nanorods of FeRu alloys, the composition depending upon the composition of the original mixture. Nanorods of the Ru and FeRu alloys encapsulated in the carbon nanotubes are also formed in the pyrolysis reaction.     

Cooperative Treatment of Metastatic Breast Cancer Using Host–Guest Nanoplatform Coloaded with Docetaxel and siRNA

Conventional chemotherapy shows moderate efficiency against metastatic cancer since it targets only part of the mechanisms regulating tumor growth and metastasis. Here, gold nanorod (GNR)‐based host‐guest nanoplatforms loaded with docetaxel (DTX) and small interfering RNA (siRNA)‐p65 (referred to as DTX‐loaded GNR (GDTX)/p65) for chemo‐, RNA interference (RNAi), and photothermal ablation (PTA) cooperative treatment of metastatic breast cancer are reported. To prepare the nanoplatform, GNRs are first coated with cyclodextrin (CD)‐grafted polyethylenimine (PEI) and then loaded with DTX and siRNA through host–guest interaction with CD and electrostatic interaction with PEI, respectively. Upon near‐infrared laser irradiation, GNRs generate a significant hyperthermia effect to trigger siRNA and DTX release. DTX reduces tumor growth by inhibiting mitosis of cancer cells. Meanwhile, siRNA‐p65 suppresses lung metastasis and proliferation of cancer cells by blocking the nuclear factor kappa B (NF‐κB) pathway and downregulating the downstream genes matrix metalloproteinase‐9 (MMP‐9) and B cell lymphoma‐2 (Bcl‐2). It is demonstrated that GDTX/p65 in combination with laser irradiation significantly inhibits the growth and lung metastasis of 4T1 breast tumors. The antitumor results suggest promising potential of the host–guest nanoplatform for combinational treatment of metastatic cancer by using RNAi, chemotherapy, and PTA.     

TiO2 Nanorod Array Constructed Nanotopography for Regulation of Mesenchymal Stem Cells Fate and the Realization of Location‐Committed Stem Cell Differentiation

As a physical cue for controlling the fate of stem cells, surface nanotopography has attracted much attention to improve the integration between implants and local host tissues and cells. A biocompatible surface TiO₂ nanorod array is proposed to regulate the fate of bone marrow derived mesenchymal stem cells (MSCs). TiO₂ substrates with different surface nanotopographies: a TiO₂ nanorod array and a polished TiO₂ ceramic are built by hydrothermal and sintering processes, respectively. The assessment of morphology, viability, gene expression, and protein characterization of the MSCs cultured on the different TiO₂ substrates proves that a TiO₂ nanorod array promotes the osteogenic differentiation of MSCs, while a TiO₂ ceramic with a smooth surface suppresses it. Periodically assembled TiO₂ nanorod array stripes on the smooth TiO₂ ceramic are constructed by a combination of microfabrication and a chemical synthesis process, which realizes the location‐committed osteogenic differentiation of MSCs. A route to control the differentiation of MSCs by a nanostructured surface, which can also control the location and direction of MSCs on the surface of biomaterials with micro‐nano scale surface engineering, is demonstrated.     

Sol-gel synthesis and photoluminescence of LaPO_4:Eu~(3+) nanorods

Monoclinic LaPO4 nanostructures with uniform rod shape have been successfully synthesized by a simple sol-gel method.The procedure involves formation of homogeneous,transparent,metal-citrate-EDTA gel precursors,followed by calcination to promote thermal decomposition of the gel precursors to yield the LaPO4 nanoparticles.Their morphologies and structures were characterized by XRD,TEM,TG-DSC and HRTEM.The results indicate that single monoclinic phase LaPO4 nanorods are readily obtained at 800 ℃ within 3 h.Furthermore,photoluminescence(PL) characterization of the Eu3+-doped LaPO4 nanocrystals was carried out.The effects of calcination temperatures and Eu3+ doping content on the PL properties were elaborated in detail.Room-temperature photoluminescence(PL) characterization reveals that the optical brightness as well as the intensity ratio of 5D0-7F1 to 5D0-7F2 is highly dependent on the calcination temperature,and the Eu0.05La0.95PO4 nanophosphor shows the relatively promising PL performance with the most intense emission.     

Two-phase eutectic cell growth modles and extension to off-mono-variant region

Abstract

CoTe and CoTe₂ nanorods with average diameter of 100 nm were synthesized by a simple hydrothermal process, and different CoTe₂ nanostructures were obtained by changing the NaOH concentration. CoTe nanorods exhibit weak ferromagnetism while CoTe₂ nanorods present paramagnetic behavior. Different magnetic behaviors occur in the other CoTe₂ nanostructures due to Na⁺ entrance into CoTe₂ crystals. A first-principles study on Na-doped CoTe₂ confirms the magnetic characteristics.